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(Space.com)   Dark matter was really hard to find because it never existed in the first place. Occam hummed a happy tune this morning, probably while shaving   (space.com) divider line 119
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19429 clicks; posted to Main » on 13 Oct 2005 at 7:48 AM (8 years ago)   |  Favorite    |   share:  Share on Twitter share via Email Share on Facebook   more»



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2005-10-13 09:14:28 AM
Em, I have a degree in Physics including a year studying Astrophysics and still didn't follow that.

/I did graduate 7 years ago
//would still have liked to have vaguely followed it
 
2005-10-13 09:16:07 AM
AFAIK thin 'infinite distance' thing is just another way of saying that 1/r, or 1/(r^2), doesn't go to zero, no matter how big r is....

In classical and Einsteinian gravity the force has infinite range, decreasing as the square of the distance without ever reaching zero.


Okay, that I can dig.
 
2005-10-13 09:22:12 AM
Cynewulf said, "... as soon as our primitive brains have developed enough to understand the mathematics of 11 dimensional Calabi-Yau spaces..."

I've made it to 10 but that last one is a doozy!
 
2005-10-13 09:24:44 AM
Matter tells space how to bend. Space tells matter how to move.
 
2005-10-13 09:25:06 AM
You people are obviously crazy.
 
2005-10-13 09:25:19 AM
A few scientists remeain skeptical.

I remeain skeptical as to whether Senior Science Writer Robert Roy Britt knows how to use a spell checker.

 
2005-10-13 09:31:58 AM
my cat's breath smells like cat food...
 
2005-10-13 09:33:08 AM
I'm very skeptical. For why, and also why dark matter isn't ad hoc fudging (as many people seem to think), see my Slashdot post.
 
2005-10-13 09:39:30 AM
Why is it hard to believe that gravity, which operates on similarly huge scales, can't have a comparable mechanism?

Let's ask this Scientician

 
2005-10-13 09:46:35 AM
Now a new study suggests there may be no such thing as dark matter.

So -- what?

You mean space is just space?

Wow! There's a concept!
 
2005-10-13 09:49:12 AM
Matter tells space how to bend. Space tells matter how to move.

Due to John Wheeler, I think. (Or at least where I first heard it.) Douglas Adams incorporated a version into HHGTTG.
 
2005-10-13 09:52:44 AM
I've always had it in for the dark matter bullshiat. Nice to see a theory that isn't asinine come forward.
 
2005-10-13 09:53:28 AM
Even if dark matter turns out to be wrong, it was never an asinine theory. There is a hell of a lot of evidence in its favor.
 
2005-10-13 10:00:43 AM
I don't see why Dark Matter is on the trimming end of Occam's Razor. We already know that there is matter that is not subject to certain fundamental forces (strange matter, which doesn't interact via strong nuclear force, for example), so positing a type of matter subject only to gravity seems a reasonable thing to do, if it helps explain some observations.

But if indeed Dark Matter doesn't exist, it would explain why Peter Jackson left Tom Bombadil out of the Lord of the Rings movie.
 
2005-10-13 10:01:10 AM
Good. Now let's debunk string theory, which is even more full of shiat.
 
ZAZ [TotalFark]
2005-10-13 10:04:24 AM
You mean space is just space?

No, space is still permeated with something invisible, but only one invisble thing (dark energy, aka the cosmological constant, aka lambda) instead of two.
 
2005-10-13 10:05:57 AM
Wait... you mean they never got around to making the calculations according to general relativity until NOW? I had just assumed they had done that already. It blows my mind that when they got a weird result using Newtonian physics, they said "there must be more matter" instead of "maybe we should use the correct equations". Feh.
 
2005-10-13 10:13:02 AM
Im not a wiz, but I never really believed when I star burned all of its fuel, it went supernova and imploded upon itself creating a black hole, or other anomaly. I believe that when all it's fuel is gone, its just gone and like a burned out match. It's not galactic science.. really.

/Nothing to see here - move along.
 
2005-10-13 10:18:05 AM
Thus, the advantage of being able to believe in two or more things at once.

I mean, really, until we have a bit of dark matter trapped in some (slightly disturbed) scientist's lab; growling and rattling the cage; then we are not going to know.

Given that, the only way to approach the problem is to hold a belief that it exists, and that it does not exist.

Testing for each possiblity is fine and dandy, but right now today we have not the tools. We are working with crystal sets in a field that requires quantum computers.

So, flip a coin; heads, tails, landing on edge, turning into cthulu on the way down. We just don't know.


Well, at least I don't.
Yet.
 
2005-10-13 10:19:08 AM
Good. Now let's debunk string theory, which is even more full of shiat.

Denying academics their ubiquitous grant flow would be like breaking into someone's home and stealing all the cash under their matress!
 
2005-10-13 10:20:45 AM
RedBaron:

Newton's equations are the correct equations, because you can estimate the magnitude of the GR correction, and it's insignificant. That's why nobody uses GR, and is why I'm extremely skeptical of this result. Indeed, there's already a preprint that claims to rebut their GR analysis.
 
2005-10-13 10:24:08 AM
Lone_Gunman:

Im not a wiz, but I never really believed when I star burned all of its fuel, it went supernova and imploded upon itself creating a black hole, or other anomaly.

And why did you never really believe that, considering all the evidence we have in favor of general relativity, which predicts black holes? And what about the observations we've made of matter falling onto dark compact objects that theory predicts are black holes and then disappearing, instead of colliding in a relativistic explosion with the surface of a "burned out object" (which we also observe, of dark compact objects that theory predicts aren't black holes).

I believe that when all it's fuel is gone, its just gone and like a burned out match.

Only some stars end up as black holes. Others end up as white dwarfs or neutron stars.
 
2005-10-13 10:28:24 AM
Lone_Gunman
Im not a wiz, but I never really believed when I star burned all of its fuel, it went supernova and imploded upon itself creating a black hole, or other anomaly. I believe that when all it's fuel is gone, its just gone and like a burned out match. It's not galactic science.. really.

Sometimes that's true, but for the largest stars the math is pretty simple. Without the balance of high-temperature, gravity pulls the star into a smaller radius. If there's enough mass, it reaches eventually becomes so dense that a black hole forms.... There's nothing mysterious about a black hole, when you think of it as a mathematical threshold instead of something from a disney movie. :)
 
2005-10-13 10:32:39 AM
Andulamb must have some serious credentials to be better than our best minds! Are you a super-hyper nuclear atomic physicists?
 
2005-10-13 10:41:18 AM
And why did you never really believe that, considering all the evidence we have in favor of general relativity, which predicts black holes?

FWIW, one of my profs in grad school, a specialist in white dwarfs and neutron stars, was a big skeptic of black holes. Basically, and to seriously oversimplify, he couldn't see a mechanism that would override the increasing degenerate neutron pressure of a collapsing core beyond the point of no return.

In other words, his position was "GR math predicts singularities, but there's no quantum mechanism to get there from here".

A perfectly reasonable position, actually, though I don't agree with it.

And the Schwarzschild (and Kerr) solution works for all non-singularity bodies, assuming you're sufficiently far away to ignore tides and mass distribution multipoles. It's the GR analogue to the Newtonian point-mass approximation for gravitation from a body. So its mathematical value transcends the prediction of black holes.
 
2005-10-13 10:45:40 AM
Robobagpiper:

FWIW, one of my profs in grad school, a specialist in white dwarfs and neutron stars, was a big skeptic of black holes. Basically, and to seriously oversimplify, he couldn't see a mechanism that would override the increasing degenerate neutron pressure of a collapsing core beyond the point of no return.

The mechanism is gravity. In GR, mass-energy density is not the only thing that gravitates: pressure (and momentum flux and stress and strain) do as well. Once pressure grows to a certain point, its force of repulsion is outweighed by its own self-gravitation. The pressure is its own downfall: it doesn't have to stop increasing.
 
2005-10-13 10:47:20 AM
...does anyone else's head hurt?
 
2005-10-13 10:49:44 AM
dark matter? when i get done with you you wont even be matter. or something
 
2005-10-13 10:55:01 AM
Ambitwistor: The mechanism is gravity.

Dude, you're going to sprain your keyboard.
 
2005-10-13 10:57:23 AM
The mechanism is gravity. In GR, mass-energy density is not the only thing that gravitates: pressure (and momentum flux and stress and strain) do as well. Once pressure grows to a certain point, its force of repulsion is outweighed by its own self-gravitation. The pressure is its own downfall: it doesn't have to stop increasing.

Yes, we're all aware that this is the standard narrative.

His point had to do with the way the degenerate neutron pressure rises with the collapse; his contention was that you couldn't get to collapse before bounce-back, without some sort of intermediate "quark star" state.

Remember, we're talking about someone who could rattle off the effects of GR on neutron star magnetospheres without looking in a book. His skepticism was very much an informed one - a minority view in the community (since the main evidence for black holes is now observational, not theoretical) - but it can't be so simply dismissed.

If there is an intermediate state he's missing, it may have come from the fact that people were just first talking about quark-gluon plasmas at this date, and had not yet produced one in the lab.

And his position may have since shifted.
 
2005-10-13 11:03:06 AM
Robobagpiper

Yes, we're all aware that this is the standard narrative.

It's not a "narrative", it's a theorem.

His point had to do with the way the degenerate neutron pressure rises with the collapse; his contention was that you couldn't get to collapse before bounce-back, without some sort of intermediate "quark star" state.

Quark stars may well be possible; there are plenty of papers on them. But they only push off the inevitable and increase the lower bound on black hole masses, not eliminate them entirely.
 
2005-10-13 11:04:54 AM
WHERE IS YOUR SCIENCE GOD NOW????
 
2005-10-13 11:09:09 AM
It's not a "narrative", it's a theorem.

No, it's not a theorem. There is no mathematical time-dependant model of black hole formation, because it would rely on quantum physics we don't have het, just a "just-so" story that lays out the broad phases. That's a narrative. I happen to accept that narrative as probably accurate in the outlines - however, some people more qualified than myself in the subject don't.

Quark stars may well be possible; there are plenty of papers on them. But they only push off the inevitable and increase the lower bound on black hole masses, not eliminate them entirely.

You're misreading. The prof's argument (F. Curtis Michel, FWIW) was that a quark star state would be necessary for the transition from degenerate neutron pressure to final collapse, not that their existence would eliminate black holes.

And as I said, he made this argument about 12 years ago. I don't know if his sentiments have changed.
 
2005-10-13 11:14:01 AM
Robobagpiper

It's not a "narrative", it's a theorem.

No, it's not a theorem. There is no mathematical time-dependant model of black hole formation, because it would rely on quantum physics we don't have het, just a "just-so" story that lays out the broad phases.


It is indeed a theorem that black hole formation results once pressure grows past a certain limit. At least in the isotropic case, and assuming that the energy conditions aren't violated.

You're misreading. The prof's argument (F. Curtis Michel, FWIW) was that a quark star state would be necessary for the transition from degenerate neutron pressure to final collapse, not that their existence would eliminate black holes.

You're not being very clear. You started out by saying that he was a skeptic of black holes because there was no mechanism to override the increasing pressure. Now you're claiming that he thought that black holes will form. Well this is not a big surprise, and it's still well possible that there are further intermediate states past "neutronium" on the way to a black hole.
 
2005-10-13 11:16:00 AM

You know, I've been writing a little essay I have entitled "It's Not Obscure".

You know those people that post something and then add the word "obscure?" complete with question mark to the post? This thread is a perfect example of "It's Not Obscure". Don't be surprised if some of you end up being quoted...

 
2005-10-13 11:23:30 AM
You're not being very clear. You started out by saying that he was a skeptic of black holes because there was no mechanism to override the increasing pressure. Now you're claiming that he thought that black holes will form.

No, I'm afraid you're just not paying attention.

The contention was that the way degenerate neutron pressure increases with density would preclude collapse to the Schwarzschild limit, without the presence of as yet unknown intermediate state to act to relieve the DNP. Without such a state, he contended, the neutron star phase was a physical dead end, whatever the bare math of GR predicted about point sources.

Any such intermediate state would have to act in analogy to the the p+e->n+v (IIRC) reaction that relieves the degenerate electron pressure in a white dwarf, and allows further collapse to the neutron star state. The neutrons would have to change into another quantum form to relieve the DNP.

As I said, the first rumblings about potential intermediate states (like quark-gluon plasmas) were just beginning to filter out of the particle physics people at this time, and I wonder if he hadn't yet taken them into account.
 
2005-10-13 11:33:35 AM
Robobagpiper

No, I'm afraid you're just not paying attention.

That turns out not to be the case. You're merely incompetent at communicating.

The contention was that the way degenerate neutron pressure increases with density would preclude collapse to the Schwarzschild limit, without the presence of as yet unknown intermediate state to act to relieve the DNP.

That had nothing to do with your original contention, which was that there was no mechanism to override increasing pressure: that he thought there was no mechanism to get from star to singularity. (That mechanism is gravity, regardless of whether it passes through an intermediate state.) Now you claim that he thought there was such a mechanism (which involves new intermediate state). You finally deemed him a "black hole skeptic", when in fact he had no problem with black holes, only on the details of the processes that form them.

Now that you've finally explained yourself correctly, it's more apparent what his claims actually were. You should have done that in the first place.

/not interested in continuing the discussion
 
2005-10-13 11:34:28 AM
Scientists have been looking for the cause of gravity for some time and have failed repeatedly.

Maybe the entire universe is spinning?
 
2005-10-13 11:44:18 AM
I would use Occam's razor differently. There are several strong theories of 'states of being' that *might* exist in the universe without us *currently* being able to detect them. One or more of these theories may account for dark matter, so until there is some evidence one way or another...

For example, energy traveling faster than the speed of light, aka tachyons. Tachyons cannot slow down to below SOL any more than ordinary energy can speed up faster than the speed of light. And yet both may "experience" gravity, and the same gravitational field may interact with both.

Another example would be quantum signature. The theory being that energy has a given "frequency" that only interacts with other energy of the same "frequency". Energy of other "frequencies" shares a different quantum universe, and the two are invisible to each other. And yet both may "experience" gravity, and the same gravitational field may interact with both.
 
2005-10-13 11:47:55 AM
I'm always in the dark, for that matter...

/nuthin'
 
2005-10-13 11:50:31 AM
Best? Correction: W O R S T Headline ever.

And I quote (let's see if HTML works for me today):
The new analysis has been submitted to the Astrophysical Journal but has yet to be reviewed by other scientists.

If it is right?

"This would remove about 25 percent of the mass of the universe, the ultimate weight-reduction program," Cooperstock said.


In other words, the concept suggested in this article hasn't been reviewed, criticized, or substantiated by anyone *except* the author(s). Last I checked, the Scientific Method required such measures before you went running around the world claiming something has been proven or disproven.
 
2005-10-13 11:51:25 AM
Angel of Death
"It's a good thing you're not pretending to be an expert, because you're not fooling anyone."

I may not know much about science but I know what I like.
 
2005-10-13 11:58:46 AM
Occam's Razor (paraphrased): the simplest explanation is most likely the correct one.

Darwin's Blade: the simplest explanation is most likely Stupidity.
 
2005-10-13 12:27:40 PM
Feh... I'll belive in black holes when I see it. Otherwise it's an academic shortcut.
 
2005-10-13 12:37:09 PM
Just so you know...I ate it.

Dark matter is a convenient answer to make the math work. It may or may not exist. It may or may not be more than one thing. If it does not exist, we need new ideas on how the universe was created, what it is made of, how long it will last, and whether or not it is the only one. Also, if it does not exist, and the whole physical universe is unbalanced does that mean it is more likely to be natural or more likely there is a supreme being?

Most likely, it exists in some form. Otherwise, Star Trek is totally wrong.
 
2005-10-13 12:54:43 PM


He who declares that dark matter does not matter, will forever be left in the dark.
 
2005-10-13 12:56:05 PM
Modified Newtonian Dynamics.

Welcome to 1989.
 
2005-10-13 01:10:51 PM
The paper is located here:
Physics Archives

It hasn't been published yet ... so take the information in the article with a grain of salt.

Both Cooperstock and Tieu work at the University of Victoria.
 
2005-10-13 01:19:44 PM
2005-10-13 11:58:46 AM wjllope

Occam's Razor (paraphrased): the simplest explanation is most likely the correct one.

Darwin's Blade: the simplest explanation is most likely Stupidity.


Ha ha... I almost choked when I read this :)
 
2005-10-13 01:35:11 PM
I don't think that I am actually intelligent enough to understand this, but is he saying that what binds galaxies together is not a large central mass, but simply a stable spot of turbulent motion, like the red spot on Jupiter?

If so, does chaos theory offer the mathematical models to work out if this is feasible?
 
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